flash/nor: Reorder drivers alphabetically

flash/nor: Reorder drivers alphabetically

To avoid conflicts between flash drivers being added, consistently use
an alphabetical sort order for the three places new drivers get added:

* Makefile.am NOR_DRIVERS (note: automake disallows a trailing backslash)
* drivers.c struct flash_driver forward declarations
* drivers.c flash_drivers array

Change-Id: Idcd6a8e12821ef10958a6b3ad7bac0dc63cadd08
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-on: http://openocd.zylin.com/3417
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>